1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for etching a platinum (Pt) layer in a semiconductor device.
2. Description of the Related Art
As the semiconductor manufacturing technology develops and its application expands, a need has developed for a semiconductor device having a large capacitance. However, it is difficult to obtain such a large capacitance using a dielectric layer having a low dielectric constant such as an oxide and/or nitride layer. Therefore, a high dielectric constant material such as ferroelectric materials, e.g., BST (BaSr)TiO.sub.3, PZT (PbZrTiO.sub.3), PLZT (Pb, La)(Zr, Ti)O.sub.3 is used. Further, a chemically stable electrode material having a high oxidation resistance at a high temperature, e.g., a platinum (Pt) layer, is required to endure the high temperature process for depositing a high dielectric material.
However, it is difficult to form a fine platinum pattern because platinum does not react well with etchants. Also, etching by-product of platinum has low volatility and it precipitates on the sidewall of a mask material during a dry etching process. In particular, it is very difficult to remove the etching by-product without damaging the mask material. Once the mask material is damaged, the storage-node platinum pattern starts to be etched, and thus the resultant surface area of the platinum pattern is decreased. The decrease in surface area of the platinum pattern results in a decrease in the capacitance of the capacitor.